After seeing the passion of workers at a construction site for the Three Gorges Dam project, Zheng Xiaoying found an unlikely source of inspiration for music.

"Personally, I was impressed by the passion of those who are working at the construction site," said Zheng, artistic director for the Xiamen Philharmonic Orchestra. "I used to think that passion or enthusiasm only has something to do with the artists and never connected it with the scientists or engineers until I stood at the site."

The song-symphony "Echo from the Three Gorges" composed by Liu Yuan and performed by Xiamen Philharmonic Orchestra, will make its premiere at the Beijing Concert Hall tonight.

Tomorrow, Zheng will lead the orchestra to play at her alma mater, China Central Conservatory of Music, celebrating the 55th anniversary of the conservatory's founding.

The story of the music dates back to early 2003 when Xiamen Philharmonic Orchestra was invited to perform in Yichang of Central China's Hubei Province, where the Three Gorges Dam is being built.

Impressed by their concert, Lu Youmei, then general manager of the China Three Gorges Project Corporation, went to Zheng with the idea of creating a symphony about the Three Gorges project.

"Lu said it could not be a work simply to sing praises for those who are working on the project," Zheng told China Daily before the rehearsal on Sunday afternoon. "It could interpret the relationship between the human beings and water or express the balance between the human beings and nature. It is a profound theme for a symphonic work, so I agreed to commission a composer to create it."

The veteran conductor soon contacted composer Liu who scored "Echo of the Earth Building" for the Xiamen Philharmonic Orchestra in 2000. The work has since won wide acclaim and gained the Golden Bell Award from the Chinese Musicians' Association.

But it was never an easy commission.

Conductor Zheng thinks highly of the work, though admitting it a difficult piece for the orchestra.

"Liu is a very serious composer who cares about every note of his composition," she said. "This work shows all his talents and devotion. And the difficult score could stimulate our orchestra members' passion when playing."

"Actually, I did not expect its complex nature and controversy until I returned to the Three Gorges two years ago. My composition 'Echo of the Earth Building' was a success, so I was supposed to continue the way that I scored that piece. And I thought I was familiar with the Three Gorges where I had paid four trips since 1983," Liu said.

"But when I travelled along the Three Gorges in 2003, I realized what I wanted to write was not what I thought of in my studio."

It finally took the composer one year to think over the theme, and one more year to finish the five-movement score.

In addition to the symphonic part, Liu composes the chorus in every movement. The lyrics are selected from the Tang poems about the Yangtze River and people's life along the river.

Liu explained that the brass, strings and woodwind and the vocals respectively represent the mountains, the river and human beings.

Liu expects the chorus to enhance the power and momentum of the work, and the classic poems to express what's on the composer's mind that the melodies can't sufficiently reflect.

In mid-January, Zheng will conduct Xiamen Philharmonic Orchestra to perform the work in Yichang where the music originated.